Reaction products of dialkyltin oxides and higher dialkyltin monohydric aliphatic saturated alcohol esters of thiomalic and thiolactic acids

ABSTRACT

Reaction products of higher dialkyltin oxides and higher dialkyltin monohydric saturated alcohol esters of thiomalic and thiolactic acid are provided, that are excellent stabilizers for polyvinyl chloride resins.

nited States Patent Brecker et al.

[72] lnventors: Lawrence R. Brecker, Brooklyn; Alfred Thee, Long Beach, both of N.Y.

[73] Assignee: Argus Chemical Corporation, Brooklyn,

[22] Filed: Jan. 22, 1971 [21] App1.No.: 109,049

Related [1.5. Application Data [62] Division of Ser. No. 788,916, Jan. 3, 1969, Pat. No.

[ July4, 1972 52 U.S.CI ..260/45.75K,260/29.1R s11 lnt.Cl.

[58] Field of Search ..260/45.75 K, 29.1 R

[56] References Cited UNITED STATES PATENTS 3,478,071 11/1969 Weisfield 260/4575 3,591,549 7/1971 Brecker et al. "260/4575 Primary Examiner-M. .1. Welsh Assistant Examiner-V. P. Hoke [57] ABSTRACT Reaction products of higher dialkyltin oxides and higher dialkyltin monohydric saturated alcohol esters of thiomalic and thiolactic acid are provided, that are excellent stabilizers for polyvinyl chloride resins.

9 Claims, No Drawings REACTION PRODUCTS F DIALKYLTIN OXIDES AND HIGHER DIALKYLTIN MONOI-IYDRIC ALIPI-IATIC SATURATED ALCOHOL ESTERS 0F 'I'HIOMALIC AND THIOLACTIC ACIDS This is a division of application Ser. No. 788,916 filed Jan. 3, 1969 now US. Pat. No. 3,642,848.

This invention relates to reaction products of high dialkyltin oxides and higher dialkyltin monohydric saturated aliphatic alcohol esters of thiomalic and thiolactic acids, and to stabilizer compositions for polyvinyl chloride resins containing such reaction products, as well as polyvinyl chloride resin compositions containing such reaction products as stabilizers.

Organotin mercaptocarboxylic acid esters because of their advantageous properties are now widely used as stabilizers for polyvinyl chloride resins. However, they do have certain disadvantages. Frequently, they are ineffective in imparting resistance to the development of early discoloration, although they may be quite effective from the standpoint of long tenn stabilization. Moreover, they may impart an unpleasant mercaptide odor to the resin. Because they are liquids and have a relatively low tin content, if they are used in large amounts in rigid polyvinyl chloride resin compositions, they may reduce the softening point of the polymer.

Canadian Pat. No. 794,373, dated Sept. 10, 1968, describes reaction products of organotin mercaptocarboxylic acid esters and organotin oxides or sulfides or hydrocarbyltin stannoic or thiostannoic acid or esters. It is indicated that the organotin oxide or sulfide reacts with the carboxylic acid groups, and that because of this, there is a minimum spacing between the Sn-S- and the carboxylate groups before reaction will take place. This spacing requires an alkylene group of the mercaptoacid that has at least two carbon atoms. Thus, the alphamercapto acids do not undergo the reaction, thus excluding least expensive and most commonly used of the organotin mercaptocarboxylic acid esters, the thioglycolate esters.

In accordance with the instant invention, it has been determined that higher dialkyltin oxides and higher dialkyltin monohydric aliphatic saturated alcohol esters of thiolactic acid and thiomalic acids, both alpha-mercaptocarboxylic acids, react to form homogeneous liquids that are compatible with polyvinyl chloride resins, and that are excellent stabilizers therefor, imparting good long term stability as well as superior resistance to the'development of early discoloration, superior, in fact, both to the dialkyltin oxides and to the dialkyltin thiolactic and thiomalic acid esters, taken separately. The fact that this reaction takes place at all is evidently due to some unknown critical structural relationship between the dialkyltin oxides and the dialkyltin thiolactic and thiomalic acid esters. The reaction does not take place with such organotin oxides and thioglycolic'acid esters, with the exception of dioctyltin oxide and dioctyltin thioglycolate esters. The fact that these acid esters are both alpha-mercapto acid esters is evidently not a disabling factor in the reaction, contrary to what is said in Canadian Pat. No. 794,373, and the reaction is therefore entirely unexpected and inexplicable.

The invention is applicable to any dialkyltin salt of monohydric aliphatic saturated alcohol esters of thiolactic and thiomalic acids in which the alcohol residue has from about one to about 18 carbon atoms, such as for instance, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, hexyl, isohexyl, heptyl, octyl, isooctyl, 2-ethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, palmityl, myristyl and stearyl esters of such acids.

If the dialkyltin salt of the thiolactic or thiomalic acid ester is not available, it is also possible to employ a mixture of the stoichiometrically equivalent amounts of the corresponding thiolactate or thiomalate ester (2moles) and dialkyltin oxide lmole), which react in situ to form the dialkyltin bis(thiolactate ester) or bis(thiomalate ester).

The invention is also applicable to any dialkyltin oxides in which the alkyl has from 4 to 8 carbon atoms, such as the dibutyl, isobutyl, amyl, hexyl, isohexyl, heptyl, octyl, isooctyl and 2-ethylhexyl tin oxides. in addition, the dialkyltin dichlorides can be used, in the presence of alkali, such as sodium or potassium hydroxide, evidently because they form the dialkyltin oxides in situ in the presence of the alkali. Consequently, reference to the dialkyltin oxides will be understood to encompass dialkyltin dichlorides and alkali.

The reaction products are easily prepared by blending and heating a mixture of the dialkyltin oxide and the dialkyltin salt of an alcohol ester of thiolactic or thiomalic acids at an elevated temperature at which reaction occurs within the range from about 50 to about 250C. and preferably from about to about 200C. A diluent such as toluene, benzene and xylene can be used, but is unnecessary. The dialkyltin oxide is insoluble in the dialkyltin thiolactic or thiomalic acid ester at the beginning of the reaction, and the progress of the reaction is readily observed by dissolution of the dialkyltin oxide. When all of the dialkyltin oxide has dissolved, and a homogeneous liquid is formed, reaction is essentially complete, but heating can be continued for another 1% hour to 1 hour, to ensure that all of the dialkyltin oxide has reacted. The reaction is complete in from 30 minutes to 1 hour, but longer heating times up to 5 hours can be used, if desired. These homogeneous liquids are completely compatible with polyvinyl chloride resins in the proportions required for stabilizing efl'ectiveness.

An improvement in the stabilizing effectiveness of the dialkyltin thiolactic or thiomalic acid ester is obtained with the reaction therewith of very small amounts of dibutyltin oxide. As little as 2.0 percent dibutyltin oxide will enhance the effectiveness of the resulting reaction product in increasing resistance of the resin to the development of early discoloration when heated. There is no upper limit on the amount of dialkyltin oxide that can be reacted, except that imposed by homogeneity of the reaction product; in amounts in excess of about 50 percent, the homogeneity of the reaction product may be disadvantageously affected; the upper limit is reached when no more dialkyltin oxide dissolves. Preferably from 25 to 40 percent by weight of dialkyltin oxide is reacted with the dialkyl thiolactic or thiomalic acid ester.

These reaction products have an outstandingly high tin content, for dialkyltin mercaptoacid ester derivatives. The tin content is within the range from about 10 percent to about 35 percent tin, depending on the amount of dialkyltin oxide reacted. Products having a tin content of from 15 to 25 percent are preferred as stabilizers. Consequently, small amounts are quite effective in stabilizing effectiveness. From about 0.1 to about 10 percent by weight of the resin is usually employed.

The reaction products are useful with all types of polyvinyl chloride resins, in which vinyl chloride is present in the polymer molecule in major proportion, up to 100 percent. Thus, polyvinyl chloride homopolymers as well as copolymers of vinyl chloride with other copolymerizable monomers, such as ethylene, vinyl acetate, vinylidene chloride, acrylonitrile, methyl acrylate and acrylic acid can be stabilized by the reaction products of the invention. The polyvinyl chloride resin compositions can also include the usual adjuncts, such as plasticizers, as in semi-rigid and plasticized formulations, the rigid formulations containing less than 10 percent plasticizer, the sernirigid formulations containing from 10 to 18 percent plasticizer, and the highly plasticized formulations containing from 18 to 75 percent plasticizer. Other stabilizers can be added, as well as antioxidants, such as phenols.

The following Examples in the opinion of the inventors represent preferred embodiments of the invention.

EXAMPLE 1 Dibutyltin oxide (41.5 grams) was added to dibutyltin-bis- (monoisooctyl thiolactate) (222 grams) which heated heated at C. and stirred for three hours. In the course of the reaction, the dibutyltin oxide (which was initially insoluble), dissolved in the mixture, and a homogeneous, light yellow liquid was formed. The tin content was found to be 22.5 percent.

The liquid was employed without further procesing as a stabilizer in comparison with dibutyltin-bis-(monoisooctyl thiolactate) as a control, on an equal tin weight basis in the following resin formulation:

Parts by Weight Diamond 40, polyvinyl chloride resin homopolymer 100 Blendex 401, styrene-butadieneacrylonitrile copolymer l Wax E lubricant 0.25 Stabilizer Amount shown in Table l and II The components were blended, and the resulting mixture was then milled and heated on a two-roll mill at 350F. for minutes, after which the mixture was homogeneous, and was sheeted off. The resulting sheet was cut into strips, and the strips heated in an oven at 350 and at 375F. in separate tests, in parallel with like compositions formulated using only the dibutyltin-bis-(monoisooctyl thiolactate) as the stabilizer. The results obtained were noted, and are summarized in Tables I and Il.

TABLE I Example l Time Control A Reaction Product of of Dibutyltin-bis-(monoiso- Dibutyltin oxide and Heating octyl thiolactate) l7,8% dibutyltin-bis-(mono- (Minutes) Sn) 24 parts isooctylthiolactate) (22.5% Sn) 2 parts Initial colorless colorless l5 light yellow colorless 30 yellow colorless 45 yellow colorless 60 yellow very pale yellow 75 yellow very pale yellow 90 yellow pale yellow 105 yellow very light yellow 120 yellow light yellow TABLE II Example 1 Time Control A Reaction Product of of Dibutyltin-bis-(monoiso- Dibutyltin oxide and Heating octylthiolactate)( 17.8% dibutyltin bis-(mono- (Minutes) Sn) 2.4 parts isooctylthiolactate) (22.5% Sn) 2 parts lnitial colorless colorless l 5 yellow colorless 30 yellow very pale yellow 45 yellow light yellow 60 yellow-brown edges yellow-brown edges 75 brown brown 90 very dark brown very dark brown It is apparent from the data that the reaction product gives a very significant improved resistance to the development of early discoloration, as compared to dibutyltin-bis- (monoisooctyl thiolactate), when tested at both 350F. and 375F.

EXAMPLE 2 Dibutyltin oxide (24.9 parts) was added to dibutyltin-bis- (diisooctyl thiomalate) (195 parts) which was heated to 115C. with stirring, and the temperature maintained for 3 hours. The dibutyltin oxide initially was insoluble in the mixture, but as the reaction continued, it dissolved, and finally at the conclusion of the reaction time a homogeneous light yellow-liquid was formed. The tin content was found to be l6.l percent.

This reaction product was used without further processing as a stabilizer in a polyvinyl chloride resin composition, in parallel to dibutyltin-bis-(diisooctyl thiomalate) as a control. The following formulation was used:

Parts by Weight Diamond 40, polyvinyl chloride resin homopolymer lOO Blendex 401, styrene-butadieneacrylonitrile copolymer l0 Wax E lubricant 0.25

Stabilizer Amounts shown in Tables Ill and IV TABLE III Example 2 Time Control B Reaction Product of of Dibutyltin-bis-(diiso- Dibutyltin oxide and Heating octylthiomalate)( 12.1% dibutyltin-bis(di- (Minutes) Sn) 3.6 parts isooctylthiomalate) (l6 l% Sn) 2.3 parts Initial cloudy, colorless clear, colorless l5 cloudy, colorless clear. colorless 3O cloudy, very pale yellow clear, colorless 45 cloudy, pale yellow clear, colorless 60 cloudy, light yellow clear, very pale yellow 75 cloudy, light yellow clear, very pale yellow cloudy, yellow clear, light yellow I05 cloudy, yellow clear, yellow 120 cloudy, yellow clear, yellow TABLE IV Example 2 Control B Reaction Product of Time Dibutyltin-bis-(diisooctyl) Dibutyltin oxide and of thiomalate) (121% Sn) dibutyltin-bis-(di- Heating 3.6 parts isooctylthiomalate) (l6.l%Sn) 2.3 parts Initial colorless colorless l5 cloudy, pale yellow clear, very pale yellow 30 cloudy, light yellow clear, very pale yellow 45 cloudy, yellow clear, pale yellow 60 cloudy, yellow clear, yellow 75 cloudy, dark yellow clear, dark yellow 90 cloudy, very dark clear, very dark yellow yellow reddish brown reddish brown dark brown dark brown It is apparent from the data that the reaction product gives an improved resistance to the development of early discoloration, as compared to dibutyltin-bis-(diisooctyl thiomalate when tested at both 350F. and 375F.

Having regard to the foregoing disclosure, the following is claimed as the inventive and patentable embodiments thereof:

1. A polyvinyl chloride resin composition comprising a polyvinyl chloride resin and a homogeneous liquid reaction product containing from about 10 to about 35 percent tin, that is compatible with polyvinyl chloride resins, and that is a particularly effective polyvinyl chloride resin stabilizer, comprising the product of the reaction at from about 50 to about 250C. of a dialkyltin oxide in which the alkyl has from four to eight carbon atoms, with a dialkyltin monohydric aliphatic saturated alcohol ester of thiolactic or thiomalic acid in which the alcohol residue has from about one to about 18 carbon atoms.

2. A polyvinyl chloride resin composition according to claim 1 comprising a polyvinyl chloride homopolymer.

3. A rigid polyvinyl chloride resin composition in accordance with claim 1 comprising up to percent plasticizer.

4. A polyvinyl chloride resin composition according to claim 1 in which the dialkyltin thiolactate or thiomalate ester is an ester of an alcohol having from four to 12 carbon atoms.

5. A polyvinyl chloride resin composition according to claim 1 in which the dialkyltin ester is a dibutyltin bis-(octyl thiolactate) or dibutyltin bis-( octyl thiomalate) ester.

6. A polyvinyl chloride resin composition according to claim 1 in which the amount of dialkyltin oxide is at least 2 up to about 50 percent by weight of the reaction product.

7. A polyvinyl chloride resin composition according to claim 1 in which the amount of dialkyltin oxide is at least 5 up to about 40 percent by weight of the reaction product.

8. A polyvinyl chloride resin composition according to claim 1 in which the tin content is from about 15 to about 25 percent.

9. A polyvinyl chloride resin composition according to claim 1 in which the dialkyltin oxide is derived from dialkyltin dichloride and alkali.

* i f i UNITED STATES PAliLNT OFFICE CERTIFHJATE 0F CQRRECTION Patent No. 3,674,737 Dated y 1972 Inventor(s) Lawrence R. Breaker and Alfred Thee I t is certified that error appears in the above-identified patent and the t said Letters Patent are hereby eorrec ted as shown below:

. Column 1, line 7 "high" should be higher .1

Column 2, line 67 "which heated heated" should be which was heat ed O Column 3, lme 2'? TABLE] 350F. 25 I Example I Time Control A Reaction Product of of Dibutyltin-bis-(monoiso- Dibutyltin oxide and Heating octyl thiolactate) l7.8% dibu!yltin-bis-(monoa (Minutes) Sn) 24 parts isooctylthiolactate) (22.5% Sn) 2 parts 30 Initial colorless colorless l light yellow colorless 30 yellow I colorless 45 yellow colorless 3 5 M) yellow very pale yellow 75 yellow very pale yellow Q 90 yellow pale yellow I05 yellow very li ht yellow I yellow light yellow 40 should be TABLE I Q E l l xamp e Time Comm 1 Reaction Producl of of Dihutyltin-bis-(monoiso- Dibutyltin oxide and Heating oclyl thiolactute) I73; dibutyltin-his-(mono- (Minutes) Sn) 2.4 parts isooctylthioluclate) (22.5% Sn) Zparts a initial colorless colorless l5 light yellow colorless 30 yellow colorless yellow colorless 35 yellow very pale yellow L. v yellow very pale yellow I 950 yellow pale yellow J 0 yellow very light yellow I20 yellow light yellow Page 2 of Ll UNI'lEl) S'lA'lES PA'llilN'l OFFECE CERTIFICATE OF C OlilllEUllON Patent 150. 674! 737 Dated July 4, 1972 Inven:or(s) Lawrence R. Brecker and Alfred Thee It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 46 TABLE" Example I 45 Time Control A Reaction Product of of Dibulyllin-bls-(monoiso- Dibulyllin oxide and Healing oclylthiolaclale l 7.8% dibulyltin bis-(mono- (Minutes) Sn) 2.4 parts isooctylthiolacrate) (22.5% Sn) 2 pans Initial colorles colorless l yellow colorless yellow very pale yellow yellow light yellow j yellow-brown edges yellow-brown edges 55, brown brown l very dark brown very dark brown should be TABLE n i Example I 5' Time Comm. Reaction Product of of Dibulyllin-bis-(monoiso- Dibuiyltin oxide and Healing oclyllhiolaclateX 17.8! dibulyllin bis-( mono- (Minutes; Sn) 2.4 pans isooctylthiolactale) (22.5% Sn)2pam l 50 1 lnirial colorless colorless l 5 yellow colorless .10 yellow very pale yellow 45 yellow light yellow 60 yellow-brown edges i yellow-brown edges 55 7S bro n bro n 90 very dark brown very dark brown Page3 f 4 a UNITED STATES PA'IEN'I OFFICE CERTIFICATE OF CURRECTIQN Patent 250. 74, 7 7 Dated July 4, 1972 Lawrence R. Brecker and Alfred Thee It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

9 Column 4, line 28 TABLE m Example 2 Time COI'I'llOl B Reaction Pmduu (:f Of Dibulyllin-hisldilso- Dihulyltin nude and 0 Healing oclyhhiomulalefl lZJK dihulyllmhls (d:-

(Minutes) Sn) l6 parLs iymclyllhmmulmc; llhlisnyl' pdrlx lnilial cloudy, culnrless clear. Culurlcsfi 35 I cloudy, colorless Clear, C0lnrlc\\ 30 cloudy, very pale yellow clear, colurlesn 45 cloudy, pale yellow clear. cnlnrlexs 60 cloudy. light yellow clear, \ery pale ycllov.

7S cloudy, light yellou clear ery pale Q yellow 40 90 cloudy, yellow clear, lxghl yellou 10s cloudy, yellow cleanyellou 5 I cloudy, yellow clear, yellow 5 should be TABLE I" w. Example 2 E Time B i Reaclion Product of 0f Dibutyllin-hisldiisn- Dihutyllin "ml: and JG Healing nctyllhinmulalefl 12 I'll dihutylumhls (Lll- I {Minute-s) Sflj 3155mm iyxwlyllhmmulnlc) l l lninal cloudy, colorlcs clear. culmlraa l 35 I5 cloudy, colorlesfi clear. colurle 30 cloudy, very pale yellow clear, colurlexs cloudy. pale yellow clear. cnlorles cloudy. llghl yellow clear. \ery pale yellow Q cloudy, light yello clear, very pale yellow 4o cloudy, yellow clear, ligh! yellov. I05 cloudy, yellow clear, yellou I20 cloudy, yellow clear, yellou z rage 1 U1. H

UNITED STATES PATENT OFFICE CERTIFICATE OF QURRECTIQN 3,674,737

Dated July 4, 1972 It is ca and that said r- Column 4, line 48 5 TABLE IV Example 2 Control B Reaction Product of 50 Time Dlbulyllin-bis-(diisooctyl) Dlbulyllin oxide and of thlomalale) (l2.lk Sn) dibuIyltln-bis-(dia Heaung 3.6 parts isooclylthiomalale] U (lfilQSnllSparls Inmal colorless colorless l5 cloudy, pale yellow clear. \er, pale yellow 55 n dy. lighr yellow clear. cr pale )cllou cloudy, C"0\\ clga pale u 60 cloudy. yellow clear. yellou 75 cloudy, dark yellow d d 31 90 cloudy, very dark clear. m aayk 60 yellow il 105 reddish brown reddish bro n I20 dark brown dark bro n should be 45 TABLE IV Exam le 2 comm B ReacuorFProduc! of Time Dlbulyltin-bis-(diisooctyl) Dibulyllin oxide and of lhiomalalefllllF-i Sn; dibulyllin-uis-(di- Heating 3.6 parts isooclyllhiomalale) (l6.liSn) 2.3 parts Initial colorless colorless I IS cloudy, pale yellow clear. ery pale f yellow 30 cloudy. light yellouclear. \ery pale yellou 4S cloudy. yellow clear. pale yellow cloudy, yellow clear. yellow cloudy, dark yellow clear. dark yellou cloudy, very dark clear, very dark 60 yellow ellou I05 reddish brown reddish broun I20 dark brown dark brown Signed and Scaled tlu's Seventeenth Day Of August 1976 [SEAL] Attest:

RUTH C. MASON A Nesting Officer C. MARSHALL DANN Commissioner vj'larents and Trademarks 

2. A polyvinyl chloride resin composition according to claim 1 comprising a polyvinyl chloride homopolymer.
 3. A rigid polyvinyl chloride resin composition in accordance with claim 1 comprising up to 10 percent plasticizer.
 4. A polyvinyl chloride resin composition according to claim 1 in which the dialkyltin thiolactate or thiomalate ester is an ester of an alcohol having from four to 12 carbon atoms.
 5. A polyvinyl chloride resin composition according to claim 1 in which the dialkyltin ester is a dibutyltin bis-(octyl thiolactate) or dibutyltin bis-(octyl thiomalate) ester.
 6. A polyvinyl chloride resin composition according to claim 1 in which the amount of dialkyltin oxide is at least 2 up to about 50 percent by weight of the reaction product.
 7. A polyvinyl chloride resin composition according to claim 1 in which the amount of dialkyltin oxide is at least 5 up to about 40 percent by weight of the reaction product.
 8. A polyvinyl chloride resin composition according to claim 1 in which the tin content is from about 15 to about 25 percent.
 9. A polyvinyl chloride resin composition according to claim 1 in which the dialkyltin oxide is derived from dialkyltin dichloride and alkali. 